Coated article and process of making



Patented Sept. 7, 1954 COATED ARTICLE AND PROCESS OF MAKING Alfred Arnold, Hermann Unterguggenberger, and Ernst Schmidt, Munich, Germany, assignors to Wacker-Chemie G. m. b. H., a corporation No Drawing. Application December 3, 1951, Serial No. 259,724

Claims priority, application Germany December 7, 1950 4 Claims.

This invention relates to the production of coatings which are intended primarily to protect vats, suspension devices and the like from the deleterious action of acids, alkalis, solvents, heat, etc., and it has for its object to provide a novel and improved process for this purpose.

Another object of the invention is to provide a simple and economical impervious coating for the above purpose which is universally resistant to all of the destructive influences to which it may be subjected.

Various other objects and advantages will be apparent as the nature of the invention is more fully disclosed.

Galvanizing or electro-plating plants require vats, and, for the objects to be nickel-plated or chrome-plated for example, they require suspension devices or hangers, which are proof against acids, alkalis, solvents and heat, and which are also non-conductors of electricity. Of course it is known to provide these devices with an insulating laye of varnish. However, there is no single varnish which satisfies all of the foregoing requirements, and it is too complicated and uneconomical to provide individual vats and hangers treated with various types of varnishes, one of which, for example, is proof against solvents, another against acids, etc.

We have now discovered, that by covering the vats and other objects with polyvinyl chloride, and heating same in situ to the extent to produce disintegration, we produce a novel coating which is proof against all of the above-mentioned destructive influences. Since this disintegration of the polyvinyl chloride pursuant to the present invention (at temperatures preferably of 160- 180 C., and, in the case of polyvinyl chloride paste, starting at about 150 C.) has the effect of discoloring the material to an extent which would be undesirable for conventional purposes, and the appearance of disintegration has heretofore been carefully avoided, such high burningin temperatures have not heretofore been applied to polyvinyl chlorides.

However, we have found to our surprise that through the application of our heating process the resistance properties of the coating are so greatly enhanced that it becomes proof in practice against all influences of solvents, lyes, acids, electric current, etc., which have come under our observation. The application of the coating, for instance upon vats, hanger devices and the like, can bedone in any suitable manner with solutions, pastes and the like. The objects can also be clipped in polyvinyl chloride solutions or, with the object of greater adhesiveness for the coating, may be heated up beforehand. The polyvinyl chloride can also contain additions which are conventional in the case of varnishes, such as softeners, pigments, and the like.

In the burning-in of our polyvinyl chloride coating we have further found that, in the case of hanging devices and the like made of zinc, and alloys containing zinc or which are coated with zinc, the coating may be burned-in at C. only for about half an hour, if it is desired to prevent the formation of bubbles and scales. As a result of this short burning-in period, or because of the temperature, the coating is proof against hot solvents and hot water only to a limited degree, so that it is not suitable for galvanic plants.

However we have now also discovered that this shortcoming is eliminated if the zinc-coating objects are provided with a zinc-less (zinc-free) coating before being covered with polyvinyl chloride, for instance if they are chrome-plated or copper-plated in advance of such coating. In this way the unfavorable reaction of the zinc upon the polyvinyl chloride is eliminated. Copper-plated brass objects, for instance, are obtained without the bubbles When the polyvinyl chloride coating is burned-in at C. for two hours. The coating is then deep black and highly lustrous and, as a result of its tight impervious texture, meets all the requirements which are imposed upon it by galvanizing plants.

Although certain specific embodiments are set forth herein for purposes of illustration, it will be evident to those skilled in the art that the invention is capable of various modifications and adaptations within the scope of the appended claims.

The invention claimed is:

1. Process for coating objects which comprises covering same with a coating consisting of polyvinyl chloride and heating the covered object to a degree to cause discoloration of the coating due to disintegration of the polyvinyl chloride and to obtain a black, lustrous, impervious film on the object.

2. Process for coating objects which comprises covering same with a coating consisting of polyvinyl chloride and heating the covered object to a temperature of about 150-190 C. until the polyvinyl chloride has discolored due to disintegration and forms a black, lustrous, impervious film on the object.

3. Process for coating objects which comprises covering same with a coating consisting of polyvinyl chloride paste and heating the latter to a degree to cause discoloration due to disintegration of the polyvinyl chloride and to obtain a black, lustrous, impervious filmontheobject.

4. An object havinglan exterior =black, flustrous, impervious coating consisting of disintegrated polyvinyl chloride which is resistant to the action of electroplating processes and produced in accordance with the process of claim 1.

References Cited in the file of this patent :Number UNITED STATES PATENTS 

1. PROCESS FOR COATING OBJECTS WHICH COMPRISES COVERING SAME WITH A COATING CONSISTING OF POLYVINYL CHLORIDE AND HEATING THE COVERED OBJECT TO A DEGREE TO CAUSE DISCOLORATION OF THE COATING DUE TO DISINTEGRATION OF THE POLYVINYL CHLORIDE AND TO OBTAIN A BLACK, LUSTROUS, IMPERVIOUS FILM ON THE OBJECT. 